Fine-tune JSONL Validator
Validate chat fine-tuning datasets and inspect local token estimates
About
Paste one chat fine-tuning sample per line to validate JSON syntax and message schemas. Switch between OpenAI and Anthropic formats to catch role and turn-order issues, then inspect deterministic line-level token estimates and role statistics.
About this tool
Validate chat JSONL schema, report line-level errors, and estimate token distribution locally in your browser. Fine-tune JSONL Validator runs in the browser on DevTools. There is no signup, and your input stays on this device unless the tool explicitly performs a live network lookup.
What this tool does not do
- Fine-tune JSONL Validator is a free in-browser utility, not a hosted API. It does not keep server-side history and is not a substitute for production verification in your own stack.
How do I use this tool?
How do I use Fine-tune JSONL Validator?
Open Fine-tune JSONL Validator, enter or paste your input, and copy the result. The page works without an account.
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